Storm water and septic systems have been in wide use for many years, including for example, pre-molded polyethylene galleries. An advantage to utilizing these galleries is that they are lightweight, easy and quick to install and relatively inexpensive.
Pre-molded polyethylene galleries have increasingly been utilized for leaching and drainage systems. Such a system is disclosed in U.S. Pat. No. 5,087,155 to DiTullio (“the '155 patent”), the disclosure of which is incorporated by reference, which discloses a drainage and leaching field system comprising vacuum-molded polyethylene galleries that are designed to be connected and locked together in and end-to-end fashion.
The galleries disclosed in the '151 patent comprise a single pre-molded polyethylene layer with an arch-shaped configuration having upstanding ribs running transverse to the length of the gallery. The ribs provide compressive strength to the gallery where, often it is desired to install the galleries under parking areas and under roadways. However, because the galleries are made of only a single layer the rocks and or debris falling into or on the gallery during, for example, installation, can cause damage to the gallery. Additionally, where the galleries are exposed to, for example, a warm or hot caustic such as may be encountered at a chemical treatment plant, the structural integrity of the gallery can be compromised if the chemical causes damage to the walls of the gallery. Additionally, it is virtually impossible to determine a level of fluid in the gallery without direct visualization of the interior of the gallery.
U.S. Pat. No. 6,854,925 to DiTullio (“the '925 patent”), the disclosure of which is also incorporated by reference, discloses a multi-layer plastic gallery including a first exterior layer forming a smooth continuous surface along a substantial length of the gallery; a second middle layer forming a plurality of spaced apart upstanding ribs along a length of the gallery; and a third interior layer forming a smooth continuous surface along a second substantial length of the gallery. The '925 patent further discloses that one benefit of the configuration is that it allows for a low-friction surface on the interior walls for the quick removal of storm water runoff. While the smooth inner wall does present a reduced friction surface, the problem of providing a gallery capable of withstanding damage due to, for example, rocks or other heavy objects impacting the surface of the gallery during installation is still a factor.
For example, while providing a multi-layer walled structure will provide additional strength to the gallery, the exterior layer and possibly the middle corrugated support layer may become damaged (e.g. cracked) if a large object impacts the exterior of the gallery. Additionally, the galleries disclosed in the '925 patent do not allow or provide for a remote determination of a level of fluid in the gallery without direct visualization or the insertion of an instrument to perform the measurement.